1. Field of the Invention
The present invention relates to a decorative tape adhesive molding and particularly to a decorative tape adhesive molding adapted for use as a car bumper molding which is cut into a predetermined length so as to be set up along a curved surface of a bumper.
Although a bright foil-including bumper molding including a decorative tape of bright foil having a decorative portion layer of a metal thin film formed between a transparent resin film layer and a backing layer will be described mainly as an example of the decorative tape adhesive molding, the decorative tape adhesive tape is not limited thereto.
Incidentally, Japanese Patent Publication No. Hei. 4-10, and Japanese Utility Model 7-35792 etc. are preceding related art though they have no influence on the novelty of the decorative tape-including molding according to the present invention.
The present application is based on Japanese Patent Application No. Hei. 10-338132, which is incorporated herein by reference.
2. Description of the Related Art
FIG. 1 is a perspective view showing an example of a bumper 11 to which a molding according to the present invention is applied.
FIG. 2 is a sectional view showing an example of a bright foil-including molding 12 according to the present invention.
FIG. 3 is an enlarged sectional view showing a portion 3 in FIG. 2.
The bright foil-including molding 12 is constituted as follows. Bright foil 16 is fusion-bonded to a molding body 14. A molding body molding material (hereinafter referred to as xe2x80x9cbody molding materialxe2x80x9d) is a thermoplastic elastomer (TPE) composition. The bright foil 16 is constituted by a backing layer 18, a transparent resin film layer 20, and a metal vapor deposition film (decorative portion layer) 22 interposed therebetween. Though not shown, an adhesive agent layer (primer layer) is generally interposed between the backing layer 18 and the metal vapor deposition layer 22.
The molding body 14 has been molded of a soft polyvinyl chloride (PVC) resin composition mixed with a large amount (50 parts or more) of a plasticizer so as to be given elastomeric characteristic.
For example, a metal vapor deposition film 22 of chrome, or the like, is formed on a transparent resin film (carrier film) (transparent resin film layer 20 ) of polyethylene terephthalate (PET), or the like, by a physical method such as sputtering, ion-plating, thermal vapor deposition, or the like. An adhesive agent is applied onto the metal vapor deposition film 22. A backing sheet (backing layer 18) is adhesively bonded to the metal vapor deposition film 22. The resulting material thus prepared is cut so as to be shaped like a tape for use as the bright foil tape 16.
To fusion-bond the bright foil 16 to the molding body 14, a PVC type resin composition capable of being (thermally) fusion-bonded to the molding body 14 has been used as a resin composition (backing forming material) for forming the backing layer 18.
Incidentally, a pressure-sensitive double coated tape is generally integrally stuck to the back surface of the molding body 14 in order to attach the molding body 14 to a bumper 11.
There is, however, a tendency that use of PVC is limited because of environmental problems of nowadays. For this reason, thermoplastic elastomer (TPE), especially, so-called non-polar TPE such as polyolefin type TPE, polystyrene type TPE, or the like, which is light in weight and excellent in antiweatherability, has been noticed as a substitute for PVC to be used as a molding material for the molding body.
When the molding body is to be molded of one of these non-polar TPE materials, it is necessary that the backing layer 18 on the fusion-bonding side of the bright foil 16 is also formed of a resin composition (backing forming material) containing, as its main component, the same non-polar polymer resin as the non-polar TPE for the purpose of fusion-bonding the backing layer 18 to the molding body.
The inventors, however, have found that sufficient fusion-bonding strength (peel strength) can be hardly obtained (particularly under a high-temperature atmosphere) when bright foil (decorative tape) having a backing layer formed of a polyolefin type resin composition is fusion-bonded to a molding body molded of a polyolefin type TPE composition generally used as non-polar TPE, and that bent portions of the molding body crumples when a bending process is applied to the molding body.
In view of the above description, an object of the present invention is to provide a decorative tape adhesive molding in which sufficient fusion-bonding strength can be obtained between a molding body and a decorative tape even under a high-temperature atmosphere and in which bent portions of the molding body hardly crumples when a bending process is applied to the molding body.
In the process of eagerly trying to make development to solve the aforementioned problem, the inventors have found that the aforementioned problem can be solved when the main-component resin of the non-polar resin composition for forming the backing layer of the decorative tape is constituted by the same kind polymer as the hard phase-forming polymer of non-polar TPE and the tensile modulus of elasticity of the backing layer is selected to be not smaller than a predetermined value. Thus, the inventors have concluded by thinking out a bright foil-including molding having the following configuration.
A decorative tape-including molding comprises a molding body made of a molding body forming material (body molding material) containing a non-polar thermoplastic elastomer (non-polar TPE) as a base polymer, and a decorative tape integrally fusion-bonded to the molding body, the decorative tape including a transparent resin film layer, a backing layer made of a resin composition (backing forming material) capable of being fusion-bonded to the body molding material, and a decorative portion layer interposed between the transparent resin film layer and the backing layer. The backing forming material is constituted by a resin composition containing the same kind of polymer as a hard phase-forming polymer of the non-polar TPE or containing a resin polymer having a melting point of not lower than 100xc2x0 C. and capable of being fusion-bonded to the hard phase-forming polymer of the non-polar TPE.
To secure sufficient fusion-bonding strength, the amount of the same kind of polymer contained in the backing forming material as the hard phase-forming polymer of the non-polar TPE is preferably not smaller than a value enabling the polymer to form a sea phase (continuous dispersion phase).
In the configuration, it is preferable from the point of view of preventing the molding from crumpling in a molding-bending process that the tensile modulus of elasticity (ASTM D 638) of the backing layer is from 80 to 1000 MPa.
When, in the above description, the transparent resin film layer of the decorative tape is made of polyethylene terephthalate (PET) and applied to a molding which crumples easily in the molding-bending process, the effect of the present invention becomes remarkable desirably.
When the body molding material is polyolefin type TPE (TPO) containing a hard phase of polypropylene (PP), it is preferable, from the double points of view of fusion-bonding characteristic of the backing layer to the molding body and prevention of crumpling of the molding body, that the backing forming material is a resin composition containing 50% by weight of random PP.
Incidentally, when the transparent resin film layer of the decorative tape is made of a polyfluorocarbon type resin, the problem of crumple occurrence in the molding body is not required to be taken into account. As a result, the tensile modulus of elasticity of the backing layer is not required to be in the predetermined range as in the case where the transparent resin film layer is made of PET.
Incidentally, in any case, it is preferable from the point of view of securing fusion-bonding strength that the amount of random PP is not smaller than 70% by weight.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.